Taking a cue from Cal's list of possible future topics let's try an area we haven't seen in some time. Backlighting: ".. technique that lights a performer, object, or poster from behind rather than from above, below, or in front, in order to create a dramatic effect" from answers.com

We have all been sabotaged by the consequences of unintended backlighting. This weeks challenge is to demonstrate the use of backlighting for dramatic effect.